I am indian national and came to germany for study in 2003

After finishing studies I stared working since 2006 and in 2011 got Niederlassungserlaubnis.

I am also married to indain national who came here on family reunion visa in 2008.

My son was born last month in Erlangen and standesamt told me to wait for 14 days for the mail from Ausländerbehörde regarding German nationality of my  Son according to Geburtsortprinzip.

I waited for a month and went today for information regading decision and the Standesamt told me that my son wont get the German nationality and I went to decision making person in auslaenderamt.

The Frau their told me that the decion was made negative regarding my Son's german nationality due to the fact that I dont fullfill rightfull stay of 8 years in Germany as stay from 2003 till 2006 were regarded as study time and from 2006 till 2012 makes 6 years.

So despite having Niederlassungs Erlaubniss &
Stay of more then 9 years 2003-2012, My son was denied the birth right of Getting German nationality.

Is this treatment understandable or is it normal in Bayern  that they dont consider a student time and even deny a nationalty based on Geburtortsprinzip?

Please any experienced member can suggest a way or give an advice to get a right for my son?

Thanks a lot in advance

Even one of my friend had same situation in Munich.
In Bayern student time is not considered for their newly born children citizenship.

Baba